Pawl freewheel clutch

ABSTRACT

The invention is directed to a freewheel clutch which transmits torque in two directions of rotation and controls the blocking pawls by control rings which are held back by friction rings ounter to the rotary motion and by guide extensions and pivot journals of blocking pawls guided in radial slots in guide extensions which move the blocking pawls out of or into engagement with the assigned support recesses of the inner part into a disengaged or engaged position. While, for instance, the one blocking pawl is moved into the torque transmitting position, simultaneously, the other blocking pawl is moved out of the position permitting torque transmittal. This assures a short response travel and with it a rapid switchover from the one driving direction to the other without interfering with the freewheeling motion.

BACKGROUND OF THE INVENTION

The invention is directed to a freewheel clutch with two coupling parts,namely an inner part and an outer part, as well as blocking pawls inbetween both parts pivotable by means of a control mechanism. Thecontrol mechanism comprises a frictional arrangement applying brakingagainst rotation into an engaged position and a disengaged position withrespect to both rotational directions. Two sets of blocking pawls areprovided which are configured to transmit torque in opposite rotationaldirections and to freewheel in the respective other direction ofrotation, wherein all blocking pawls are pivotably supported in recessesdistributed across the circumference of one clutch part and can bebrought into engagement with support recesses in the other clutch part.

Such a freewheel clutch is, for instance, known from DD-PS 1 39 154,DE-GM 1 888 456 and DE 34 26 108 A1. Herein, both sets of blocking pawlsare controlled in such a way that the pivoting of the pawls to be movedinto the disengaged position occurs by means of a shifting spring actedupon by a frictional arrangement or by a cam disk. The engagement of theblocking pawls occurs by the force of a compression spring assigned toeach blocking pawl after appropriate penetrations in the shifting springhave been opened or the cam has been moved out of engagement with thecorresponding locking pawl.

Furthermore, in a freewheeling arrangement known from DE-AS 16 25 730, ablocking pawl is provided, which is designed to have two arms and ispivotably supported in the driving part. One arm of the blocking pawlserves to provide a torque transmission in one direction of rotation andthe other arm serves to provide a torque transmission in the otherdirection of rotation.

A braking mechanism has the effect that, depending upon the drivingrotational direction, the twin armed blocking pawl is pivoted into theappropriate recess. For the reversal process from one rotationaldirection into the other rotational direction respectively, passagethrough a zero position is required where the blocking pawl is not incontact with any of the butt faces provided in the outer part for torquetransmission. Thus, twice the travel in circumferential direction wouldbe covered when passing from one torque transmittal direction to theother, than would be required in order to snap into one or the othertorque transmittal direction from the zero position. Furthermore, theentire torque must be directed through the journal bearing of thelocking pawl. The bearing must thus be sufficiently large in order tocarry these forces.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide afree-wheel clutch designed for torque transmittal in two rotationaldirections, where the response travel, when switching from onerotational direction to the other, is short and where, in addition, theforces resulting from the torque transmittal do not have any effect uponthe support of the blocking pawls.

Pursuant to this object, and others which will become apparenthereafter, one aspect of the present invention resides in the blockingpawls of the two sets being respectively pivotable by means of aseparate control ring, and the control rings are held to be respectivelyrelatively rotatable with respect to the coupling part where theblocking pawls are supported.

In a refinement of the invention the control rings are held to berotatable relatively with respect to each other through a limitedamount.

The advantage of this embodiment is that an introduction of the torqueis directly transmitted by area abutment of the blocking pawls againstthe respective recesses of the two coupling parts. The pivot bearingitself is not affected by this transmittal of the forces. In addition, ashortening of the lost motions necessary for moving the blocking pawlsfrom one torque transmittal direction into the other torque transmittaldirection is achieved. While the one set of blocking pawls is moved outof the torque engagement position, simultaneously the blocking pawls ofthe other set are moved into the appropriate support recesses forswitching into the other rotational direction. This considerablyshortens the response time when reversing directions.

Another advantage of this arrangement is that the freewheeling sidebeing the overrunning side is excited vibration-wise by the single partdesign of the pawls, which promotes the clutch function.

In another embodiment of the invention, a friction ring is assigned toeach of the separate control rings, and the friction rings arerespectively held in a receiving ring, which rings are supported to bestationary and non-rotatable or which are supported upon a coupling partso that a braking force can be applied against rotation.

In a further embodiment, the blocking elements are guided in therotational direction by means of a frictional lock at that coupling partwhich comprises the support recesses. The blocking elements, in case theassociated coupling part rotates faster in the same rotational sensethan the coupling part supporting the blocking pawls, hold the overtakenblocking pawls in a freewheeling position, meaning in a position wherethey are lifted off the respective support recesses.

It is achieved by this embodiment that, in the situation where thedriven coupling part runs faster than the driving coupling part, theblocking pawls acted upon by the control rings and the friction rings inthe torque transmittal direction, do not rachet in the support recesses,rather they are held in a position lifted off the recesses. Theotherwise typical ratcheting noise therefore does not exist here. Thisalso diminishes the friction during the overtaking or over-runningprocess. On the other hand, it is assured that, when the drivingcoupling part rotates again faster than the driven coupling part, theblocking elements do no longer engage at the blocking pawls and thusthese can be moved without any hesitation into the appropriate supportrecesses ready for torque transmittal.

In order to achieve a precise control of the blocking pawls in all theoperational situations, the control rings are equipped with acylindrical friction surface and, facing away from the friction surface,they are equipped with radial guide extensions for the one set ofassociated blocking pawls, which extensions engage into appropriateguide means of the blocking pawls.

Preferably, the friction rings are designed as rotary shaft lip seals,which rest upon a friction face of the associated control ring preset bya spring.

It is proposed furthermore that the blocking pawls be equipped with apivot journal as guide means offset radially with respect to their pivotaxis and located entrally in their axial extent. The guide attachmentsof the control rings guide these in radial slots.

In an additional embodiment, in order to achieve a secure lifting of theblocking pawls into the over-running position out of the correspondingsupport recesses, a quantity of the blocking elements corresponding tohalf the quantity of blocking pawls are provided, which are arrangedrespectively in between the blocking pawls intended for torquetransmittal in the opposite rotational direction and which act withtheir end faces upon one of the blocking pawls depending upon therotational direction. These blocking elements are then preferablydesigned as circular ring segments, and are arranged in a groove of theassociated coupling part and are maintained by an elastic ring infrictional lock in this groove. The frictional lock of the blockingelements with respect to the assigned clutch part permits this clutchpart to overtake or overrun the driving clutch part. On the other hand,the frictional lock is sufficient in order to achieve a securedisengagement by holding the blocking pawls in a lifted-off positioncounter to the restoring force into the support recesses exerted by thefriction and control rings.

Although a support of the blocking pawls only in the recesses issufficient, it is provided in another embodiment of the invention, thatthe blocking pawls be equipped with guide journals on both ends, whichare held with play in corresponding guide bearings in the coupling partin which they are supported. The guidance with tolerance or play isrequired in order to achieve a perfect support in the support recesseson the one hand and in the recesses in which they are supported on theother hand, without any jamming occurring.

The blocking pawls are preferably designed to be L-shaped and the edges,in which the outer faces of the legs converge, form the pivot axes whichrespectively rest in the tip of the associated recesses of the clutchpart supporting them.

In a preferred embodiment, the outer part is that coupling part wherethe blocking pawls are supported in recesses. Alternately, it is howeveralso possible that the inner part is the coupling part where theblocking pawls are supported in the recesses.

In case the outer part is the coupling part where the blocking pawls aresupported, the outer part is divided and the two parts are provided withguide recesses in the parting line. The two outer parts can herein bedesigned to be identical and are held together by a bolt connection.

For reducing the friction, the receiving ring, where the friction ringsare arranged, is supported upon the external surface of the externalpart with interposition of bearing bushes.

In order to guide the blocking pawls with respect to the part supportingthem, retaining rings are provided as guide bearings, which are insertedinto bores in the outer part overlapping the guide journals and whichtransgress the guide journals.

For supporting the blocking elements, the inner part is provided with acircumferential groove centrally in its axial extent, at whose sidewalls the blocking elements are held in contact by an elastic ring. Theblocking elements respectively protrude radially out of the groove intothe intermediate space between two blocking pawls arranged back to back.

The novel features which are considered as characteristic for theinvention, are set forth in particular in the in the appended claims.The invention itsef, however, both as to its construction and its methodof operation, together with additional objects and advantages thereof,will be best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a longitudinal section through a first embodiment of afreewheeling clutch pursuant to the invention;

FIG. 2 is a section along 2--2 in FIG. 1';

FIG. 3 is a longitudinal section 3--3 through the first coupling outerpart in FIG. 4;

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a further side view of FIG. 3;

FIG. 6 is a second coupling outer part in section;

FIG. 7 is a side view of FIG. 6;

FIG. 8 is a front view of a control ring;

FIG. 9 is a side view of FIG. 8, in section;

FIG. 10 is a front view of a blocking pawl;

FIG. 11 is a side view of FIG. 10;

FIG. 12 is a section 12--12 in FIG. 10;

FIG. 13 is a side view of an inner part;

FIG. 14 is a longitudinal section through the inner part in FIG. 13;

FIG. 15 is an axial section through a receiving ring;

FIG. 16 is a section 16--16 through a further embodiment of afreewheeling clutch in FIG. 17;

FIG. 17 is a longitudinal section through the freewheel clutch in FIG.16;

FIG. 18 is a longitudinal section through a third alternative of afreewheel clutch, where the blocking pawls are assigned to the innerpart; and

FIG. 19 is a side view of FIG. 18 in section along the line I--I.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show a reversible freewheel clutch 1 in an assembledstate.

The freewheel clutch 1 comprises essentially a divided outer part 2,whose two parts are designated by 2a or 2b, the inner part 3 arrangedcoaxially in the bore of the outer part 2 as well as the blocking pawls4, 5 arranged in between. The blocking pawls 4, 5 are assigned to theouter part 2 and distributed across the circumference. They aresupported respectively in recesses 15, 16 of the outer part 2. Theblocking pawls 4, 5 are identical; however, they are received inopposite directions in the recesses 15, 16. Thus, three such blockingpawls form one set of blocking pawls, which are arranged in recesses 15.The blocking pawls point with their long legs and end faces in adirection n of the rotational direction arrow appearing in FIG. 2.Blocking pawls assigned to the additional set of blocking pawls 5 arearranged in the recesses 16 in such a way that they are directed counterto the first blocking pawls 4. Thus they point with their end facescounter to the rotational direction indicated by the direction of thearrow n.

The blocking pawls 4 and 5 are alternately arranged in circumferentialdirection in the recesses 15 or 16 and are made to be L-shaped. The longleg is designated with 7 and the short leg with 6. The outer faces 8, 9of the two legs 6, 7 converge in the edge 11, which also forms thecutting edge, which is provided for support in the tip 17 of therecesses 15, 16. The blocking pawls 4, 5 are provided with guidejournals 12 on the ends in the region of the short leg 6, which journalsare shaped as quarter circles in cross-section. These quarter circlesare received in corresponding retaining rings 30. The retaining rings 30are inserted into bores 31 of the outer part 2. Herein, the bore 31 forthe retaining rings 30 is arranged in such a way that it crosses overthe guide journals 12, so that the retaining rings 30 can be pushed overthe guide journals 12. The retaining rings 30 embrace the guide journals12 with play, so that the blocking pawls 4, 5 can adjust themselves inthe appropriate recess 15 or 16 without any constraints arising, and canbe brought with their pivot axis 11 into contact with the tip 17 of therecess 15, 16 or can abut without any constraints at correspondingabutment faces of the recesses 15, 16 in order to be able to transmittorque. The abutment of the blocking pawls 4, 5 is achieved by the outerface 8 of the short leg 6 relative to the outer part 2 and by the endface 10 in the support recesses 18 which are designed to besawtooth-shaped and extend to be distributed across the circumference ofthe inner part 3. This can be discerned particularly from FIGS. 13 and14, where the inner part 3 is shown as an individual part. The supportrecesses 18 comprise, respectively, two support faces 19 and 20 at whichthe blocking pawls 4, 5 come to rest. In the embodiment example in FIGS.1 and 2, the blocking pawl 4 for instance comes into contactrespectively with the support faces 19, while the blocking pawls 5 comeinto contact at the support surfaces 20. Herein a torque transmittal inthe direction of the arrow n is achieved for the blocking pawls 4, whilethe blocking pawls 5 achieve a torque transmittal counter to thedirection of the arrow n.

It can be discerned from FIGS. 1, 13 and 14 that the inner part 3 issupported in the outer part 2 on ball bearings 22. The ball bearings 22are retained in bearing seats 21 of the inner part 3 as well as bearingbores 25 in the outer part 2. They extend additionally into two covers23 and 24. The cover appearing in FIG. 1 on the left-hand side isdesignated with the numeral 23 and the other cover with the numeral 24.

Control rings 32, 33 are provided for guidance of the blocking pawls,meaning for synchronization of the motion of the blocking pawls 4 and 5which respectively belong to one set. These control rings cooperate withpivot journals 13 of the blocking pawls 4, 5, which pivot journals 13are fastened centrally in the axial extent of the blocking pawls 4, 5.The design of the pivot journals 13 can be especially gathered fromFIGS. 10 and 12. It can been seen, that the pivot journal 13 is offsettowards the pivot axis 11. The blocking pawls 5 or 4 belongingrespectively to one set are synchronized respectively by one controlring 32 or 33. Thus, the blocking pawls 5 are synchronized by thecontrol ring 32 and the blocking pawls 4 by the control ring 33 as faras their motion is concerned.

The two control rings are arranged in a groove 41 in the outer part 2.The groove 41 is located respectively in part in outer parts 2a and 2b.The two control rings 32, 33 comprise a cylindrically extending segment,which is provided externally with a cylindrical frictional surface 38.Facing away from the frictional surface 38 there extend guideattachments 39 in the radial direction, and in this embodiment radiallyinward, which attachments are provided with radial slots 40. The guideattachments 39 are distributed circumferentially corresponding to thearrangement of the blocking pawls 4, 5 for the guidance of which theyserve. The radial slots 40 of the guide attachments 39 serve forembracing the pivot journals 13 of the respective blocking pawls 4, 5.

The two control rings 32, 33 are arranged in such a way that they faceeach other with the region containing the guide attachment 39. The outerpart 2 is designed to be divided so that the control rings discernibleas individual parts in FIGS. 8 and 9 can protrude radially with theirguide attachment 39 into the region of the pivot journals 13 of theblocking pawls 4 or 5. The two parts of the outer part can be discernedfrom FIGS. 3 to 7. Thus, the outer part 2a shown in FIG. 1 on theleft-hand side can be discerned in FIGS. 3 to 5 and the other part 2bshown on the right-hand side in FIG. 1 can be seen in FIGS. 6 and 7. Thetwo outer parts 2a and 2b are themselves identical. However, they willbe referred to individually in order to better explain their function.

It can be discerned in the outer part 2b depicted in FIGS. 3 to 5, thatrecesses 15 and 16 are alternately provided, which serve respectivelyfor receiving the blocking pawls 4 or 5. The recesses 15, 16 areessentially triangular. Their tip 17 forms the support for the edge ofthe blocking pawls 4, 5 which edge represents the pivot axis 11. Theparting surface, this is the right-hand face towards the outer part 2acorresponding to FIG. 3, is designated by 27, while in the outer part 2bthe left face in FIG. 6 represents the parting surface and is alsodesignated with the numeral 27. It can be seen that the two outer parts2a and 2b comprise complementary turned out grooves, which together formthe groove 41 for receiving the two control rings 32, 33. The two outerparts 2a and 2b are held with their parting surfaces 27 in contact inthe assembled position shown in FIG. 1. Guide recesses 43 are providedfor passage of the guide extensions 39 associated with the control ring32, 33 radially inward into the region of the pivot journals 13 of theblocking pawls 4, 5. The guide recesses 43 belong respectively to therecesses 15 or 16. It is seen in FIG. 4, that in the outer portion 2a,to which the guide ring 32 is assigned and which serves for controllingthe blocking pawls 5, the guide recesses 43 cover the blocking pawls 5in the recesses 16 in which said blocking pawls are arranged. The guiderecesses 43 are bounded on the sides by boundary surfaces 44, 45, whichare arranged in such a way that sufficient freedom of movement space forthe associated blocking pawls 5 exists from the engagement into thedisengagement position with respect to the inner part 3. In the normalsituation however the guide extensions will not come into contact.

It is seen in FIG. 4 that three such guide recesses 43 are provided. Theother outer portion 2b depicted in FIGS. 6 and 7 comprises three guiderecesses 43 distributed across the circumference, which are assigned tothe recesses 15. These guide recesses 43 serve for the passage of theguide attachments 39 of the control ring 33, which synchronizes themovement of the blocking pawls 4.

The two outer parts 2a, 2b are provided with communicating bores 28which extend into the bearing cover 23, 24. The bearing cover 23 has athreaded bore, while the mounting cover 24 is provided with an immersedbore, in which the connecting bolts 29 are received with a bolt head,while they are threaded with a threaded end into the bores in the cover23.

The covers 23, 24 and the bolts 29 not only fasten the inner part 3 andthe two parts 2a, 2b forming the outer part 2, they also hold togetherthe frictional arrangement which controls the control rings 32, 33. Thefriction rings 34, 35 are supported upon the outer surface 42 of theouter part 2 with interposition of bearing bushes 46 and receiving rings47. The bearing bushes 46 are secured axially by guide rings 51 in theregion of the contact faces 26 of the two outer parts 2a, 2b at whichthe covers 23, 24 rest. The bearing bushes 46 are retained in a bore 48of the two receiving rings 47. Each of the two receiving rings 47comprises a turned-in groove 63 which receives one friction ring 34 or35. The friction ring 34 cooperates by means of its contact surface 36with a frictional surface 38 of the control ring 32. The friction ring34 is retained with its outer surface 37 in the turned-in groove 63 ofthe receiving ring 47 so as to be locked rotationally with respectthereto. The friction ring 35 contacts with its contact face 36 thefrictional face 38 of the control ring 33. The frictional ring 35 isassigned to the other receiving ring 47 which is also insertednon-rotatably with its outer surface 37 into the turned groove 63. Thetwo receiving rings 47 are arranged opposite each other in such a wayupon the outer surface 42 of outer part 2 that their turned grooves 63form a chamber for receiving the two friction rings 34, 35. The tworeceiving rings 47 are surrounded by a clamping ring 49 provided withattachment lugs 50, by means of which the receiving rings 47 and due tothese also the friction rings 34 can be held to be stationary withrespect to the rotating outer part 2.

If the outer part 2 is rotated in the rotational direction n in FIG. 2,around the axis of rotation X--X of the freewheel clutch 1, thefrictional lock between the friction ring 35 with the friction face 38of the control ring 33 causes a holding back of the control ring 33 withrespect to the rotary motion of the outer part 2, so that because of thearticulation of the blocking pawls 4, these are pivoted out of thedisengaged position shown in FIG. 2 inward into the engaged position, sothat their end faces 10 come to rest on the face 19 of the supportrecess 18 of the inner part 3. Simultaneously, the control ring 32 isheld back with respect to the rotary motion in the rotational directionn because of the frictional lock between the friction ring 34 and thecontrol ring 32. However, because of the arrangement of the blockingpawl 5 oriented counter to the blocking pawl 4, there occurs adisengagement of the blocking pawl 5 with its end position 10 out ofcontact with the support surface 20 of the support recess 18.

The blocking pawl 5 is then moved out of the engaged position shown inFIG. 2 into the position occupied by the blocking pawl 4 in the diagramin FIG. 2. Thus, it recedes radially from the control recesses 18 in theinner part 3. Therefore, a relative motion between the control rings 32,33 in the respective guide recesses 43 with respect to the outer parts2a, 2b occurs, wherein they respectively approach one of the boundaryfaces 44, 45 of the outer parts 2a, 2b without, however, coming to restat these.

Pivoting of the blocking pawls 4, 5 occurs respectively around the pivotaxis 11 with assist from the pivoting moment exerted by the controlrings 32 or 33 upon the journals 13 of the blocking pawls 5 or 4.

An overtaking or overrunning or freewheeling by the inner part 3 canoccur also counter to the direction n in the position shown in FIG. 2,meaning when a torque transmittal counter to the rotational direction noccurs by means of the pawls 5 from the outer part 2 to the inner part3. Herein the blocking pawls 5 slide at the support faces of the supportrecess 18 radially outwardly counter to the displacement force exertedby the friction ring 34 for movement into the engaged position. Thefrictional lock permits also a reset, meaning a relative motion of thecontrol ring 32 with respect to the friction ring 34 for backwardrotation or return rotation of the blocking pawls 5. If a state again isreached where the outer part 2 attains the rpm of the inner part 3counter to the direction of rotation n or exceeds same, there occursagain automatically an engagement of the locking pawls 5 into theposition shown in FIG. 2 and an entrainment of the inner part 3 by theouter part 2. For mounting on a driving or driven component, thefreewheel clutch 1 is provided with threaded bores 26 in the region ofthe mounting cover 24. The inner part 3 can be connected by means of ashaft insertable into the mounting bore 59, for instance, with the partto be driven.

So as to prevent a ratcheting of the blocking pawls 4 or 5 upon theouter surface of the inner part 3 in the freewheeling position, meaningwhen the inner part 3 rotates faster than the outer part 2, respectivelyprovided for the driving function, since said blocking pawls are actedupon because of the friction rings depending upon the rotationaldirection in direction of the radial motion into the support recess, anarrangement of blocking elements has been configured in a refinement ofthe solution described in FIGS. 16 and 17. In between two blocking pawls4 and 5, respectively arranged in opposite directions, blocking elements55 are located in a groove 53 of the inner part 3. The groove 53 islocated approximately in the middle of the region of the parting surface27 of the outer part 2. The blocking elements 55 are designed to beshaped as quarter circles. Respectively two blocking elements areprovided for acting on two blocking pawls 4, 5 follow each other butpoint in opposite directions.

Between the blocking elements 55, an elastic ring 56 is inserted withprestress, so that the blocking elements 55 are pressed against the sidewalls 54 of the groove 53 and are kept in frictional lock or frictionalengagement. Radially, the blocking elements 55 project so far from thegroove 53 of the inner part 3 that they protrude into the region of theblocking pawls 4, 5. The blocking pawls 4, 5 have faces 14 against whichend faces 61 of the blocking elements 55 come to rest. In case the innerpart 3 rotates faster in the rotational direction n in FIG. 16 than theouter part 2, the blocking elements 55 are carried along in therotational direction n due to frictional engagement and run up againstthe butt face 14 of the blocking pawl 4, and lift the locking pawl,counter to the frictional force exerted upon the blocking pawls 4 by thefriction ring 35 and the control ring 33, out of the associated supportrecess 18 of the inner part 3. When the outer part 2 is overtaken by theinner part 3 in a rotational direction counter to the rotationaldirection n, the end face 21 of the blocking element 55 comes intocontact with the butt face 14 of the other blocking pawl 5. In theversion shown in FIGS. 16 and 17, four blocking pawls are providedoverall, with respectively two blocking pawls 4 and two blocking pawls 5in each rotational direction. Correspondingly, a quantity of blockingelements corresponding to half the quantity of blocking pawls 4, 5, thustwo pairs of blocking elements 55, are provided.

Apart from the friction ring control explained in connection with theembodiments of FIGS. 1 to 15, where the receiving rings and with themthe friction rings 34, 35 are permanently retained to be stationary,meaning non-rotatably because of the clamping ring 49, there can also beone braking disc 57 assigned to the single receiving ring 47 as can beseen from FIGS. 16 and 17. The brake disc 57 can be acted uponselectively by a braking force by means of a brake shoe 58. It is,however, also conceivable that the brake arrangement comprising thebrake disc 57 and the brake shoe 58 is configured as an electromagneticbrake. If we are dealing with an externally actuatable brake, it ispossible, if effectively a switching process is desired, that a brakingmoment can be exerted upon the brake disc 57 upon change of rotationaldirection.

Apart from the above, the freewheel clutch 1a corresponds essentially tothe version in FIGS. 1 and 2. Only the friction rings 34, 35 are in thiscase designed as rings with a quadratic cross-section In addition, theblocking pawls 4 or 5 are constructed to be divided, and their twoindividual parts are connected with each other by a socket pin 64.

The blocking pawls 4, 5 are assigned to the inner part 38 in the versionshown in FIGS. 18 and 19. This means that the recesses 15 and 16supporting same are located in the inner part 3, while the supportrecesses 18 are located in the outer part 2. In this case, the innerpart 3 is the respectively driving part, while the outer part 2 isdriven. The friction rings 34, 35 act correspondingly upon the innerpart 3 and the control rings 32, 33 assigned to the inner part 3.

The outer part 2 and the inner part 3 are supported opposite each otherby means of ball bearings 22. In this embodiment, the guide means 13 arenot arranged in the middle region of the blocking pawls 4, 5; rather,they extend proceeding from one end face of the blocking pawls 4, 5. Thearc-shaped design of the outer contour of the guide means 13 discerniblefrom FIG. 19, serves as a contact face for the friction rings 34 or 35.The arc-shaped guide faces of the guide means 13 which pertain to theblocking pawls 4, have a larger diameter than the guide faces of theguide means 13 which pertain to the blocking pawls 5. For the rest ofit, the guide means 13 constructed as extensions which are assigned tothe blocking pawls 5 are constructed to be longer axially than the guidemeans pertaining to the blocking pawls 4. Both control rings 32, 33 haveflanges 65 directed outward, which are held to be stationary, meaningnonrotatably, or however they can be held to be influenced by a brake.

While the invention has been illustrated and described as embodied in afreewheel clutch, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by letters patent isset forth in the appended claims:
 1. A freewheel clutch, comprising:twocoupling parts, namely an inner part and an outer part; and blockingpawls in between both coupling parts pivotable by means of a controlmechanism having a friction arrangement for braking against rotation,the pawls being pivotable into an engaged position and a disengagedposition with respect to both rotational directions, a first set and asecond set of blocking pawls being provided, which are configured totransmit torque in opposite rotational directions and freewheel in arespective other direction of rotation, all the blocking pawls beingpivotably supported in recessed distributed across the circumference ofone coupling part and engageable into support recesses in the othercoupling part, the blocking pawls (4, 5) of the first est and the secondset being respectively pivotable by separate control rings (32, 33),which control rings (32, 33) are held respectively to be rotatablerelative to the coupling part (2) which supports the blocking pawls (4,5).
 2. A freewheel clutch according to claim 1, wherein the controlrings (32, 33) are respectively relatively rotatable to a limitedextent.
 3. A freewheel clutch according to claim 1, wherein a frictionring (34, 35) is assigned to each separate control ring (32, 33), andthe friction rings (34, 35) are respectively retained in a receivingring (47), which is supported on a coupling part (2) so as to benon-rotatable stationary or so as to be brakeable against rotation.
 4. Afreewheel clutch according to claim 1, and further comprising blockingelements (55) which are guidable in a rotational direction by frictionallock at an associated coupling part (3) which has the support recesses(18), so that if the associated coupling part (3) rotates faster in acommon rotational direction than the coupling part (2) supporting theblocking pawls (4), the overrun locking pawls (4, 5) are held in afreewheel position in which they are lifted out of the support recesses(18).
 5. A freewheel clutch according to claim 1, wherein the controlrings (32, 33) are provided with a cylindrical friction surface (38)and, facing away from the friction surface (38), are provided forblocking pawls (4, 5) forming part of one set, with radial guideextensions (39) which engage with corresponding guide means (13) of thelocking pawls (4, 5).
 6. A freewheel clutch according to claim 5,wherein the friction arrangement includes friction rings (34, 35) whichare rotary shaft lip seals and which rest upon the friction surface (38)of an associated control ring (32, 33) prestressed by a spring (37). 7.A freewheel clutch according to claim 5, wherein the blocking pawls (4,5) have a pivot axis (11), and are provided with a pivot journal (13)radially offset with respect to the pivot axis (11) which forms a guidemeans centrally within the axial extent of the pawls, the guideextensions (39) of the control rings (32, 33) guide the journals (13) inradial slots (40).
 8. A freewheel clutch according to claim 4, wherein anumber of blocking elements (55) corresponding to half the number ofblocking pawls (4, 5) is provided, which blocking elements arerespectively arranged in between two blocking pawls (4, 5) provided fortorque transmittal in opposite rotational directions, the blockingelements having end faces (61, 62) which act upon one of the blockingpawls (4, 5) depending upon the rotational direction.
 9. A freewheelclutch according to claim 4, wherein the blocking elements (55) areconfigured as circular ring segments and are arranged in a groove (53)of the associated coupling part (3) and are frictionally locked in thegroove (53) by an elastic ring (56).
 10. A freewheel clutch according toclaim 1, wherein the coupling part (2) has guide bearings (30), theblocking pawls (4, 5) being equipped on both ends with guide journals(12) which are held with play in corresponding of the guide bearings(30) of the coupling part (2) supporting them.
 11. A freewheel clutchaccording to claim 1, wherein the blocking pawls (4, 5) are L-shaped andhave legs (6, 7) with outer surfaces (8, 9) having edges which convergeto form a pivot axis (11), which edges respectively rest in a tip (17)of an associated recess (15, 16).
 12. A freewheel clutch according toclaim 1, wherein the coupling part in which the blocking pawls (4, 5)are supported in recesses (15, 16) is the outer coupling part (2).
 13. Afreewheel clutch according to claim 1, wherein the coupling part inwhich the blocking pawls (4, 5) are supported in recesses (15, 16) isthe inner coupling part (3).
 14. A freewheel clutch according to claim12, wherein the outer part (2) is radially divided into two parts (2a,2b) which are provided with guide recesses (43) in a plane (27) dividingthe two parts.
 15. A freewheel clutch according to claim 3, wherein thecoupling part in which the blocking pawls (4, 5) are supported inrecesses (15, 16) is the outer coupling part (2), the receiving ring(47) being supported upon the outer surface (42) of the outer part (2)with interposition of bearing bushes (46).
 16. A freewheel clutchaccording to claim 10, wherein the coupling part in which the blockingpawls (4, 5) are supported in recesses (15, 16) is the outer couplingpart (2), and further comprising retaining rings (30) provided as guidebearings, which are inserted into bores (31) of the outer part (2)overlapping the guide journals (12) and extending beyond the guidejournals (12).
 17. A freewheel clutch according to claim 9, wherein thecoupling part in which the blocking pawls (4, 5) are supported inrecesses (15, 16) is the outer coupling part (2), the coupling part (3)is an inner part (3) which is provided with a circumferential groove(53) centrally of its axial extent, against whose side walls theblocking elements (55) are held in contact by the elastic ring (56) sothat the blocking elements (55) protrude respectively radially out ofthe groove (53) and into an intermediate space of two oppositelyarranged blocking pawls (4, 5).